• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)

Stuck intake valves, Why?

Share this page

Bruce,
I have no idea, as I don't know any history of the engine and I am no expert. Is there oil getting to the rocker shaft? The valve stems could be dry or have carbon build up on them. I suppose you could try putting some string through each plug hole in turn and then turn the engine by hand to see if you can pop the valves shut. Certainly needs more investigation.
Nick
 
With the rocker in fully open position, use a piece of soft metal on top of the valve stem or rocker, and give them in turn a sharp rap with a hammer to rapidly compress the spring and hopefully the valve will snap close.

But if it happened once, it will again, so in the end, I would pull the head, take it apart, and do what repairs are needed.
 
Bruce, I saw you'd posted this in both MG and Triumph forums and opted to reply here.

It's my understanding that there are some slightly different stem clearances that may be specified depending on the material of both the guides and the valves. Sorry, I don't know the specifics. However, since the head was recently worked on and all 4 valves seized, the guides probably weren't reamed to the correct size. You may be able to unseat them using a brass hammer to gently tap the tops of the valve stems. I agree with Ray tough, if it happened once it will happen again and the head should probably come off.

There is also the chance that not enough oil is getting to the head. If the B-series engine works the same as the A-series (sorry... it's literally been 25 years since I've worked on an MGB) then the rocker oil is fed up through the head, up through a rocker pedestal, then into the tubular rocker shaft. If you put the pedestals on in the wrong order the head could have been running dry. Without sufficient lube the rockers would certainly seize given time.

EDIT:
I see on the other thread that I misinterpreted what you said. I thought this engine's head had been reworked. Sorry. You'll have to ignore most of my post above. As they said on the other thread the stems may just be gummed up with corrosion and varnish from the time without use. You probably still need to take the head off and clean the stems and valve guides to address this.
 
Back
Top